Method and apparatus for allocating channel bandwidth in wireless internet protocol television systems

ABSTRACT

A method and apparatus for allocating channel bandwidths in a wireless IPTV system is provided. The method includes measuring, if an additional service offering request is received in a saturation channel state, remaining execution times until a service of each terminal that is currently receiving a service is terminated, and setting a minimum of the measured remaining execution times to a unit time; calculating a securable channel bandwidth per the unit time with respect to each terminal that is currently receiving a service; and allocating, if the summation of the securable channel bandwidths per the unit time is equal to or greater than a channel bandwidth required to provide the additional service, the requested channel bandwidth in order to provide the additional service.

PRIORITY

This application claims priority to an application filed with the KoreanIntellectual Property Office on Mar. 11, 2009 and assigned Serial No.10-2009-0020742, the content of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to wireless Internet protocolTeleVision (IPTV) systems, and more particularly, to a method andapparatus that can efficiently manage bandwidths to preserve channelsfor additional users in a Video on Demand (VoD) service of a wirelessIPTV system.

2. Description of the Related Art

Internet Protocol TeleVision (IPTV) systems provide multimedia servicesvia IP networks that guarantee the quality, security and reliability ofthe multimedia services. The multimedia services include television,video, audio, document, graphic, data services, etc. IPTV services mayalso be classified into real-time broadcast services and Video on Demand(VoD) services.

Unlike the real-time broadcast services, which are deployed throughbroadcast methods, VoD services are deployed through unicast methods, sothat a maximum number of available users is identical to the number ofavailable channels. As the market of the wireless IPTV systems graduallyincreases, IPTV services will be provided to a large number of users.Therefore, it is expected that current bandwidths cannot properly coveroperations to an increased number of users. Therefore, a method isrequired to efficiently manage the limited bandwidth and provideadditional services to users.

The conventional traffic control technology used in IPTV systems candetect states of an IPTV system at any time as well as variably controlthe bandwidth and the amount of data transmission, by receiving afeedback of the amount of data buffered in a terminal and continuing tomonitor the network. Although the conventional traffic controltechnology efficiently uses the existing bandwidth, the conventionaltechnology is disadvantageous in that it cannot provide services toterminals beyond the maximum number of available channels. Therefore,while all users are using bandwidths allocated to a VoD service withinthe limited bandwidth, if additional users request the service, a methodis required to provide the service to these additional users.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above problems, andprovides a method and apparatus that can allocate channel bandwidths toovercome limitations regarding the restricted number of users that canuse a VoD service in a wireless IPTV system.

The present invention further provides a method and apparatus that canallocate channel bandwidths to secure channels for additional userswhile all bandwidths for a VoD service are being used, thereby providingthe VoD service to a greater number of users than the number of userswho could previously use the service according to conventional methods.

In accordance with an embodiment of the present invention, the presentinvention provides a method for allocating channel bandwidths in awireless IPTV system, the method including measuring, if an additionalservice offering request is received in a saturation channel state,remaining execution times until a service of each terminal that iscurrently receiving a service is terminated, and setting a minimum ofthe measured remaining execution times to a unit time; calculating asecurable channel bandwidth per the unit time with respect to eachterminal that is currently receiving a service; and allocating, if asummation of the securable channel bandwidths per the unit time isgreater than or equal to a channel bandwidth required to provide theadditional service, the requested channel bandwidth in order to providethe additional service.

In accordance with another embodiment of the present invention, thepresent invention provides an apparatus for providing a wireless IPTVservice, including a channel bandwidth calculating unit and a channelbandwidth allocating unit. The channel bandwidth calculating unitmeasures, if an additional service offering request is received in asaturation channel state, remaining execution times until a service ofeach terminal that is currently receiving a service is terminated, andsets a minimum of the measured remaining execution times to a unit time.It also calculates a securable channel bandwidth per the unit time withrespect to each terminal that is currently receiving a service. Thechannel bandwidth allocating unit allocates, if a summation of thesecurable channel bandwidths per the unit time is greater than or equalto a channel bandwidth required to provide the additional service, therequested channel bandwidth in order to provide the additional service.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of certain embodiments of the presentinvention will become more apparent from the following detaileddescription in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram illustrating a channel allocation structure in awireless IPTV system;

FIG. 2 is a diagram illustrating a configuration of a wireless IPTVsystem;

FIG. 3 is a flow chart illustrating a method for controlling generaltraffic in a wireless IPTV system;

FIG. 4 is a flow chart illustrating a method for allocating channelbandwidths through a VoD service of a wireless IPTV system according toan embodiment of the present invention;

FIG. 5 is a flow diagram illustrating a process of allocating channelbandwidths to users' terminals that have requested a VoD service in amethod for allocating channel bandwidths according to an embodiment ofthe present invention; and

FIG. 6 is a schematic block diagram illustrating a wireless IPTV systemaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, various embodiments of the present invention are describedin detail with reference to the accompanying drawings. The samereference numbers are used throughout the drawings to refer to the sameor similar parts. Detailed descriptions of well-known functions andstructures incorporated herein may be omitted to avoid obscuring thesubject matter of the present invention.

FIG. 1 is a diagram illustrating a channel allocation structure in awireless IPTV system.

Referring to FIG. 1, contents provided by the wireless IPTV system, aredivided into real-time broadcast content 101 and VoD content 102. Thereal-time broadcast content 101 and the VoD content 102 are allocated todifferent bandwidths of channels 103 that can be used by the wirelessIPTV system. For example, in FIG. 1, the real-time broadcast content 101is allocated to a broadcast channel 106 with a certain bandwidth and theVoD content 102 is allocated to a unicast channel 105 with bandwidthsthat differ according to the users who request contents. In order toefficiently transmit the VoD content 102, a technology for allocating avariety of channel bandwidths is proposed to efficiently manage thelimited bandwidth of the unicast channel 105.

The channel bandwidth allocation technology unit 104 allocates availablechannels to users, in consideration of the entire state of the IPTVsystem, which may include the number of users accessing the system,system resources, service quality, etc. Unlike wired IPTV systems, awireless IPTV system based on a wireless network must efficiently uselimited bandwidth. Therefore, wireless IPTV systems preferably requirethe channel bandwidth allocation technology 104.

FIG. 2 is a diagram illustrating a configuration of a wireless IPTVsystem.

Referring to FIG. 2, the wireless IPTV system includes a content system200, a server system 210, an IP network 220, a wireless network 230, andsubscriber terminals 240.

The content system 200 stores and manages the VoD content 201 and thereal-time broadcast content 202, which are provided wireless IPTVsystem, separately. The content system 200 performs the conversion ofdata format (Moving Picture Experts' Group (MPEG)-2, H.264/ScalableVideo Coding (SVC), etc.), which can be played back by the subscriberterminals 240, and then transmits the converted data to the serversystem 210.

The server system 210 controls the VoD content 201 and real-timebroadcast content 202, transmitted from the content system 200, andtransmits the VoD content 201 and the real-time broadcast content 202 tothe subscriber terminals 240.

The server system 210 includes a browser server 211, a control server212, and a streaming server 213. The browser server 211 provides anentire interface through which the subscriber terminals 240 can selectcontents from a list of contents. The control server 212 manages serverstates, and performs log analysis and monitoring operations. Inparticular, the control server 211 considers the features of thewireless network 230, such as packet loss, frequent error occurrence,delay time, etc. The control server 211 also considers the features ofthe subscriber terminals 240, such as limited resources, mobility, etc.In order to smoothly play back multi-media in the subscriber terminals240, the codec should be light, i.e., the codec should not cause toomuch of a burden on a processor implementing the codec.

The streaming server 213 transmits contents selected by the subscriberterminals 240. In particular, the streaming server 213 considers issuesof scalability, security, and efficiency. The streaming server 213 alsorequires a proper scheduling scheme in order to guarantee a user'sQuality of Service (QoS), and further requires an efficiency scheme thatconsiders the environment of the wireless network 230 and the subscriberterminals 240.

FIG. 3 is a flow chart illustrating a method for controlling generaltraffic in a wireless IPTV system. The traffic control method isperformed by a server system that includes a browser server, a controlserver, and a streaming server. The traffic control method controlsservice traffic so that the server system can adjust bandwidthsaccording to current contents stored in a buffer of a subscriberterminal and maintain an amount of data currently being buffered in asubscriber terminal to a target amount of buffered data set by the videoserver. The traffic control method according to FIG. 3 also supports astable playback of VoD content in the IPTV systems.

Referring to FIG. 3, the server system sets a target amount of data tobe buffered in a subscriber terminal, in step 301. The target amount ofdata to be buffered in a subscriber terminal refers to a minimum amountof data that the subscriber terminal must secure in order to stably playback contents without discontinuity and delay. The target amount of datato be buffered in a subscriber terminal is not affected by changes inthe amount of data transmission from the server system, even when thenetwork state is changed. The server system monitors a network, in step302, and transmits data, with the maximum bandwidth, according to thenetwork state, to the subscriber terminal, in step 303. The serversystem identifies the amount of data buffered in the subscriberterminal, in step 304. If the server system determines that the amountof data buffered in the subscriber terminal reaches a target amount ofbuffered data at 304, the server system controls the traffic by reducingthe transmission bandwidth and the transmission according to theplayback speed of the content, in step 305. If the server systemdetermines that the amount of data buffered in the subscriber terminaldoes not reach a target amount of buffered data at 304, the serversystem returns to step 303. The traffic control method can effectivelyuse the available bandwidth described above. However, the trafficcontrol method according to FIG. 3 is disadvantageous in that the methodaccording to FIG. 3 cannot provide service to terminals over the numberof maximum available terminals.

FIG. 4 is a flow chart illustrating a method according to an embodimentof the present invention for dynamically allocating and managingbandwidths allocated to subscribers according to the ratio of resourceuse (stored data and remaining playback time), and securing bandwidthsfor additional users, if an wireless IPTV system is in a channelsaturation state that exceeds the number of users who can use a VoDservice.

Referring to FIG. 4, the channel allocating method for providing aservice to a user terminal A that requests an additional service offerincludes calculating channel bandwidths that the content server cansecure, determining whether to provide a service to the user terminal A,and securing a channel bandwidth for the user terminal A, which hasadditionally requested a service by dynamically allocating channelbandwidths of user terminals that are currently receiving a VoD service.More specifically, the server receives a VoD service request signal froma user terminal A, in step 401. The server increases a count of thenumber of users that are currently using a VoD service, in step 402. Theserver determines whether the count exceeds the maximum available numberof users, in step 403.

If the server determines that the count does not exceed the maximumavailable number of users at 403, the server allocates an extra channelbandwidth to provide the VoD service to the user terminal A, in step404. In order to receive a large amount of data before the count reachesthe maximum available number of users, all of the user terminals receivethe VoD service at the maximum receivable speed before the count exceedsthe maximum available number of users.

However, if the server determines that the count exceeds the maximumavailable number of users at 403, i.e., if the server has additionallyreceived a VoD service request in a channel saturation state, therequests information regarding an executable time using only data storedin a buffer of a user terminal from among user terminals that receives acurrent VoD service, in step 405, where the executable time is referredto as a data-not-reception executable time.

If the server has received information regarding a data-not-receptionexecutable time from all the user terminals that are currently receivinga VoD service, the server measures the remaining execution time untilthe current VoD service to each user terminal is terminated, sets aminimum remaining execution time to a unit time, and calculates themaximum securable channel bandwidth per unit time, in step 406. Aminimum remaining execution time is used as a reference because a userterminal, which does not receive a service after the minimum remainingexecution time, must to return its previously allocated channelbandwidth after the unit time. Therefore, if a channel bandwidth for anadditional user can only be secured during the unit time, even when thechannel is in a saturation state, the server can provide a service tothe additional user terminal. Therefore, it is possible to provide anadditional service only if a surplus channel bandwidth necessary for anadditional user can be secured before the server stops providing aservice to one of the user terminals that are currently receiving a VoDservice. In order to calculate a securable channel bandwidth per unittime, data-not-reception executable times of user terminals (i.e.,executable times using data stored in a buffer) and a minimum requesttransmission speed required to receive a service (i.e., the lowesttransmission speed that can guarantee QoS) are required.

For convenience, one of the user terminals that is currently receiving aVoD service is referred to as user terminal B. If a data-not-receptiontime of the user terminal B is greater than or equal to the unit time,the channel bandwidth of the user terminal B can be used is as an extrachannel bandwidth during the unit time. For example, when adata-not-reception time is greater than a unit time, the channelbandwidth can be acquired by the following Equation (1).Securable channel bandwidth=transmission speed to user terminal B×unittime  (1)

If a data-not-reception time of user terminal B is less than the unittime, the channel bandwidth of user terminal B can be acquired by thefollowing Equation (2).Securable channel bandwidth=(transmission speed to user terminalB×data-not-reception executable time)+(transmission speed to userterminal B−lowest transmission speed to user terminal B)×(unittime−data-not-reception executable time)  (2)(data-not-reception executable time<unit time)

Regarding the user terminals that are currently receiving a VoD service,the maximally securable channel bandwidth can be calculated by thefollowing algorithm.

For(i=1;i=n; i++) { IF (T_(BUF) >= T_(MINREM)) Total =+ R_(i) *T_(MINREM) else Total =+ R_(i) * T_(BUF) + (R_(i) − R_(MINi)) *(T_(MINREM) − T_(BUF)) }

In the above algorithm, R_(i) denotes a current transmission speed touser terminal i, T_(BUF) denotes a data-not-reception executable time ofuser terminal i, R_(MINI) denotes the lowest transmission speed to userterminal i where a QoS can be guaranteed, and T_(MINREM) denotes a unittime. According to the algorithm, the maximally securable channelbandwidth (Total) can be calculated during the unit time (T_(MINREM))Therefore, the greater the amount of data previously received, thegreater the number of users that can additionally receive a service.

Referring to FIG. 4, the server compares the maximally securable channelbandwidth (Total) with a request channel bandwidth for providing a VoDservice additionally requested, during the unit time (T_(MINREM)), instep 407. If the server determines that the maximally securable channelbandwidth (Total) is greater than a request channel bandwidth forproviding a VoD service additionally requested, during the unit time(T_(MINREM)) at step 407, the server concludes that the server canprovide the service. In that case, the server reduces the channelbandwidth of user terminals that are currently receiving the service andsecures a request channel bandwidth for providing an additionallyrequested VoD service, i.e., a surplus channel bandwidth, in step 408.Reduction of the channel bandwidth of user terminals that are currentlyreceiving the service is performed by sorting the amount of stored databy the priority sequence, and then reducing the channel bandwidth fromthe user terminal that has the largest amount of data. After thereduction is performed in step 408, the server allocates the surpluschannel bandwidth to a user terminal that request a VoD service in step409.

However, if the server determines that the maximally securable channelbandwidth (Total) is less than a request channel bandwidth for providinga VoD service additionally requested during the unit time (T_(MINREM))at step 407, the server concludes that the server cannot provide theservice. In that case, the service provided to one of the user terminalscurrently using the service is terminated so that an additional servicecan be provided, but the available channel bandwidth is secured so thatthe server waits until the maximally securable channel bandwidth isgreater than a request channel bandwidth. The server can check the countof the number of users according to a preset time period and calculatethe maximally securable channel bandwidth. The preset time period can beset according to the performance of the system.

FIG. 5 is a flow diagram illustrating a process of allocating channelbandwidths to users' terminals that requested a VoD service in a methodfor allocating channel bandwidths, according to an embodiment of thepresent invention.

Referring to FIG. 5, a certain bandwidth per channel is allocated tobroadcast transmission channels 502 in order to provide a real-timebroadcast service. Likewise, a certain bandwidth per channel isallocated to unicast transmission channel bandwidths 501 according tousers that request contents, with respect to a VoD service. Forconvenience, it is assumed that the maximum number of available users ofthe VoD service channel 501 is four, as an example. However, othermaximum numbers may be used in accordance with the present invention.While users 1 to 3 are receiving a service, if user 4 requests a serviceat step 503, the server allocates an extra channel bandwidth to user 4.After that, if the service of the user 1 is terminated at step 504, theserver controls traffic to secure the maximum channel bandwidth withrespect to users 2 to 4.

If user 5 requests a service at step 505, since the maximum number ofavailable users has not been exceeded, the server allocates an extrachannel bandwidth to the user 5. After that the allocation in step 505,if user 6 requests a service in step 506, since the maximum number ofavailable users has been exceeded, the server calculates the maximallysecurable channel bandwidth using the bandwidth allocating methodaccording to the present invention, reduces the channel bandwidths ofusers that were receiving a service, secures a surplus channelbandwidth, i.e., a request channel bandwidth for providing anadditionally request VoD service, and allocates the surplus channelbandwidth to the user 6. Reduction of the channel bandwidth of userterminals that were receiving the service is performed by sorting theamount of stored data by the priority sequence, and then reducing thechannel bandwidth from the user terminal that has the largest amount ofdata. After the reduction is performed in step 506, if the service ofuser 2 is terminated in step 507, the server controls traffic to securethe maximum channel bandwidth with respect to users 3 to 6.

FIG. 6 is a schematic block diagram illustrating a wireless IPTV systemaccording to an embodiment of the present invention.

Referring to FIG. 6, the wireless IPTV system includes a server 600 anda terminal 650.

The server 600 includes a time information receiving unit 601, a channelbandwidth calculating unit 602, a channel bandwidth allocating unit 603,a storing unit 604, and a data transmitting unit 605. If the timeinformation receiving unit 601 receives a number of requests that isgreater than the maximum available number of users, the time informationreceiving unit 601 can receive information regarding executable timeonly using data stored in the buffer 651, i.e., data-not-receptionexecutable time information, without receiving additional data from theterminal 650 that is currently providing a service. The channelbandwidth calculating unit 602 determines whether a channel bandwidthcan be allocated to a user that additionally requests a service and thencalculates the maximally securable channel bandwidth.

The channel bandwidth allocating unit 603 compares the maximallysecurable channel bandwidth with a request channel bandwidth forproviding an additionally requested VoD service during the unit time. Ifthe maximally securable channel bandwidth is greater than a requestchannel bandwidth, the channel bandwidth allocating unit 603 concludesthat the channel bandwidth allocating unit 603 can provide a service.The channel bandwidth allocating unit 603 controls the transmissionspeed by reducing the channel bandwidths that are provided to terminalsthat were receiving a VoD service. The reduction of the channelbandwidth of users that were receiving the service is performed bysorting the amount of stored data by the priority sequence, and thenreducing the channel bandwidth from the user that has the largest amountof data. The channel bandwidth allocating unit 603 allocates a requestchannel bandwidth for providing an additionally requested VoD service toa terminal that additionally requests a VoD service.

The storing unit 604 stores the content provided through the VoDservice. The data transmitting unit 605 transmits the content stored inthe storing unit 604 to the terminals under the control of the channelbandwidth allocating unit 601.

The terminal 605 includes a buffer 652, a playback unit 652, and anexecution time measuring unit 653. The terminal 605 receives the maximumamount of data via the maximum bandwidth and stores the received data inthe buffer 651. The playback unit 652 loads and executes data from thebuffer 651. The execution-time measuring unit 653 measures an executabletime using only data stored in the buffer 651 without receivingadditional data, according to the request of the sever 600, and reportsthe executable time to the server 600. The executable time is alsoreferred to as a data-not-reception executable time.

As described above, the method and apparatus according to embodiments ofthe present invention can efficiently allocate channel bandwidths forthe VoD service in a wireless IPTV system and thus increase the numberof users who can use the service. The method and apparatus according toembodiments of the present invention can additionally allocate channelbandwidths for additional users while all channels are being used, bythe use of a dynamic bandwidth allocation technology, guaranteeing theQoS of existing users, thereby efficiently using the limited networkresources.

Although certain embodiments of the present invention have beendescribed in detail hereinabove, it should be understood that manyvariations and modifications of the basic inventive concept hereindescribed, which may be apparent to those skilled in the art, will stillfall within the spirit and scope of the embodiments of the presentinvention as defined in the appended claims.

1. A method for allocating channel bandwidths in a wireless InternetProtocol TeleVision (IPTV) system, the method comprising: receiving anadditional service offering request from a user in a channel saturationstate that exceeds a number of users who can use the service; measuringremaining execution times until a service of each terminal that iscurrently receiving the service is terminated; setting a minimum of themeasured remaining execution times to a unit time; calculating asecurable channel bandwidth per the unit time with respect to eachterminal that is currently receiving the service; summing the securablechannel bandwidths per the unit time for all terminals that arecurrently receiving the service; and allocating the requested channelbandwidth in order to provide the additional service, if a summation ofthe securable channel bandwidths per the unit time is at least equal tothe channel bandwidth required to provide the additional service.
 2. Themethod of claim 1, wherein allocating the requested channel bandwidthfurther comprises: reducing and re-allocating each channel bandwidthallocated to the terminals that are currently receiving the service. 3.The method of claim 1, wherein the service includes a Video on Demand(VoD) service.
 4. The method of claim 1, further comprising: receivinginformation regarding an executable time using data stored in buffers ofterminals from the terminals that are currently receiving a service,wherein the received information is information regarding adata-not-reception executable time.
 5. The method of claim 4, whereinthe securable channel bandwidth per the unit time with respect to aterminal B from among the terminals that are currently receiving aservice is acquired from:Securable channel bandwidth=transmission speed to user terminal B×unittime, wherein the data-not-reception executable time of one of theterminals is greater than or equal to the unit time.
 6. The method ofclaim 4, wherein the securable channel bandwidth per the unit time withrespect to a terminal B from among the terminals that are currentlyreceiving a service is acquired from:Securable channel bandwidth=(transmission speed to terminalB×data-not-reception executable time)+(transmission speed to terminalB−lowest transmission speed to user terminal B)×(unittime-data-not-reception executable time), wherein the data-not-receptionexecutable time of one of the terminals is smaller than the unit time.7. An apparatus for providing a wireless Internet Protocol TeleVision(IPTV) service, comprising: a channel bandwidth calculating unit formeasuring, if an additional service offering request is received from auser, by the apparatus in a saturation channel state that exceeds anumber of users who can use the service, remaining execution times untilthe service of each terminal that is currently receiving the service isterminated, for setting a minimum of the measured remaining executiontimes to a unit time, and for calculating a securable channel bandwidthper the unit time with respect to each terminal that is currentlyreceiving the service; a device for summing the securable channelbandwidth per the unit time for all terminals that are currentlyreceiving the service; and a channel bandwidth allocating unit forallocating, if the summation of the securable channel bandwidths per theunit time is at least greater than a channel bandwidth required toprovide the additional service, the requested channel bandwidth in orderto provide the additional service.
 8. The apparatus of claim 7, whereinthe channel bandwidth allocating unit reduces and re-allocates eachchannel bandwidth allocated to the terminals that are currentlyreceiving the service.
 9. The apparatus of claim 7, wherein the serviceincludes a Video on Demand (VoD) service.
 10. The apparatus of claim 7,further comprising: a time information receiving unit for receivinginformation regarding an executable time using data stored in buffers ofterminals from the terminals that are currently receiving a service,wherein the received information is information regarding adata-not-reception executable time.
 11. The apparatus of claim 10,wherein the securable channel bandwidth per the unit time with respectto a terminal B from among the terminals that are currently receiving aservice is acquired from:Securable channel bandwidth=transmission speed to terminal B×unit time,wherein the data-not-reception executable time of one of the terminalsis greater than or equal to the unit time.
 12. The apparatus of claim10, wherein the securable channel bandwidth per the unit time withrespect to a terminal from among the terminals that are currentlyreceiving a service is acquired from:Securable channel bandwidth=(transmission speed to terminalB×data-not-reception executable time)+(transmission speed to terminalB−lowest transmission speed to user terminal B)×(unittime-data-not-reception executable time), wherein the data-not-receptionexecutable time of one of the terminals is smaller than the unit time.